In the medical field, leads are used with a wide variety of medical devices. For example, leads are commonly used with implantable stimulators that provide electrical stimulation. Electrical stimulation may be delivered to sacral, pudendal or other pelvic nerves within the pelvic floor of a patient to alleviate a variety of disorders such as urinary incontinence, fecal incontinence, constipation, sexual dysfunction, pelvic pain, or other pelvic floor disorders. Other applications include spinal cord stimulation, gastric stimulation and deep brain stimulation. The electrical stimulation is delivered via electrodes disposed at or near the distal ends of one or more leads. Leads may also be used with implantable cardiac pacemakers that provide therapeutic stimulation to the heart by delivering pacing, cardioversion or defibrillation pulses. In that case, the leads may position the electrodes with respect to various cardiac locations so that the pacemaker can deliver pulses to the appropriate locations. Leads may also be used for sensing purposes, or both sensing and stimulation purposes.
One challenge in implementing medical leads in a medical device is the electrical coupling between a lead and circuitry of the IMD. An IMD includes a housing that houses an implantable pulse generator (IPG) containing circuitry, and a connector module that couples the lead to the circuitry, either directly or via a lead extension. The connector module includes electrical contact structures for coupling the lead to circuitry within the housing of the IMD so that therapeutic simulation can be provided through the lead, or sensed conditions can be recorded by the circuitry. The connector module must ensure reliable electrical connections between the IMD circuitry and the lead, while also maintaining a sufficient seal between the connector module and the lead to avoid ingress of body fluids into the housing, and the possibility of electric shorting between electrodes. These requirements contribute to manufacturing complexity and cost, and can make the connection of the lead to the IMD difficult for the physician.